Pallet load sensing system

ABSTRACT

The present invention relates to a system for positioning pallets to be wrapped with a pallet stretch wrap machine and to adjust operation of the wrap machine according to measurements obtained from sensors, identify the relative size of the pallet load to be wrapped in stretch film, detect misalignment of the load and thereby control activation of the wrap sequence and the speed of the film applied.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 61/890,404, filed on Oct. 14, 2013, the content of which is fully incorporated herein by reference.

BACKGROUND

Pallets of various goods are stretch-wrapped for secure transportation. Automated stretch-wrap machines are commonly used for stretch wrapping a palletized load, which include conveyor-type systems in which pallets are loaded and transported on a conveyer, and manual stretch wrap systems in which pallets are floor-loaded using a forklift or pallet jack, positioned at a wrapping machine by an operator, and then again transported by an operator after the wrapping operation. Floor-loaded stretch wrapping systems may comprise a single arm for wrapping a single pallet, or may be multi-headed for wrapping multiple pallets simultaneously. In the case of multi-head assemblies, i.e., wrapping assemblies with multiple wrapping stations, when a pallet is incorrectly positioned in any one station of the apparatus, each incorrectly loaded station will fault out and not operate while the wrapping sequence at the correctly loaded stations will operate through the sequence of covering their respective pallet load with stretch wrap. In some cases, the wrapping head of each working station will finish wrapping before the incorrectly positioned pallets can be adjusted, which results in additional operator efforts in the unloading of wrapped pallets and loading of new pallets. Further, often the pallets are positioned at the wrapping assembly such that, when one of the loads is not in proper orientation and the wrap sequence is thereby not activated or is shut down at that station, it is not possible for an operator to reach the problem due to the other pallet loads being in the way.

Additionally, due to manual positioning of the pallet in a floor-loaded system, the distance from the film prestretch device of the stretch wrap machine to the pallet may differ from one load to another. This results in a condition in which a skewed or misaligned load in a station is positioned such that there are varying distances between the load and the prestretch device as the film prestretch device rotates around the pallet. The variable distance between the load and the prestretch device requires adjustment for proper wrapping of the load, such that the film speed of the prestretch device must accelerate and decelerate the film to make up for distance changes. This causes stress on the film at the prestretch device and potential breakage of the film, resulting in failure of the wrapping operation and down-time due to the need for an operator to correct the problem. Therefore, proper positing and alignment of a load at a wrapping station is very important to ensure continued function of a stretch wrap apparatus, and which is especially important for proper operation of an apparatus having multiple wrapping stations.

In addition, it is significant for proper function of a floor-loaded pallet wrapping system to ensure that the proper tension and amount of the stretch wrap film is applied to the load. In systems utilizing a prestretch head, such adjustments may be made by altering the speed of the film being applied to the load. Such adjustment of the film speed at the prestretch head may be manually performed, requiring an operator to identify the need for an adjustment of the speed to accommodate a smaller or larger load prior to a wrapping operation. Further, challenges exist with making such speed adjustments, which may require mechanically altering the film drive mechanism, such as altering a gear ratio at the motor of a prestretch head device. Therefore, there is a need for a stretch wrapping apparatus that will automatically identify alterations of a load at a wrapping station to enable adjustment of the film speed at the prestretch head. The present invention addresses these challenges.

OBJECT OF THE INVENTION

It is an object of the invention to provide a system for positioning pallets to be wrapped with a pallet stretch wrap machine and controlling the speed of the wrapping sequence for optimal results. Specifically, the present invention is designed for use with a floor-loaded single- or multi-headed stretch wrap machine, and comprises one or more sensors which obtain measurements of a pallet load placed within the loading station area, and signals whether the pallet is correctly positioned for wrapping by the stretch wrap machine. The system ensures that the pallet is in proper position for wrapping, and, if a pallet is in an incorrect position as determined by the laser sensor, immediate action can be taken by the operator of the pallet transport machine to correct the fault prior to initiating wrapping. It is also an object of the present invention to obtain the measurements of the distance between the stretch wrap machine prestretch device and the exterior surface of the placed pallet, and communicating these measurements to the prestretch device to predetermine how much film will be needed to wrap a pallet and when the film will be needed.

The system of the present invention offers several benefits, including: (i) the ability to use thinner films (which are more cost effective than thicker films), (ii) less film breaks as the acceleration and deceleration demands placed on the films is significantly less, (iii) a smoother unwind of film ultimately provides a higher force to load throughout the pallet, as film that is accelerated and decelerated stretches film too far not allowing the film to recover and hold the pallet, and (iv) the ability to be provided with a film cost per pallet as a pallet is put into the stretch wrap machine.

Other objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth illustrative embodiments that are indicative of the various ways in which the principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the system of the present invention with one laser, shown as used in connection with a single-post, three-station floor-loaded stretch wrap apparatus;

FIG. 2 is a top plan view of the system of the present invention with two laser devices, shown as used in connection with a four-post floor-loaded stretch wrap apparatus;

FIG. 3 is a top plan view of the system of the present invention in which two sensors are directed at a single load and positioned at adjacent corners of the pallet load;

FIG. 4 is a top plan view of an alternate embodiment of the present invention, including bumper tracks on opposed sides of the pallet load and electric eyes positioned to detect the presence or absence of the load at each side of the proper position of the load in a wrapping station of a stretch wrap apparatus;

FIG. 5 is a side view of an embodiment of the present invention as shown in FIG. 4, including bumper tracks on opposed sides of the pallet load and a sensor positioned above the load and a sensor positioned adjacent the load to identify whether the load is in proper position of a stretch wrap apparatus;

DETAILED DESCRIPTION

The description that follows describes, illustrates and exemplifies one or more embodiments of the present invention in accordance with its principles. This description is not provided to limit the invention to the embodiments described herein, but rather to explain and teach the principles of the invention in order to enable one of ordinary skill in the art to understand these principles and, with that understanding, be able to apply them to practice not only the embodiments described herein, but also other embodiments that may come to mind in accordance with these principles. The scope of the present invention is intended to cover all such embodiments that may fall within the scope of the appended claims, either literally or under the doctrine of equivalents.

In a preferred embodiment, the present invention includes a pallet load sensing and control system 2 of a floor-loaded stretch wrap apparatus 4 having an arm that rotates around a pallet load 8 to wrap the load in stretch wrap (not shown). The system 2 comprises at least one sensor device 10 that emits a sensor beam 12 for measuring at least an extent of a first face 14 and a sensor beam that measures at least an extent of a second face 16 of a pallet load 8. The system 2 then generates assigned values for each the measurements derived from the sensor 10. Preferably, the assigned measurement values will include a measurement of the width of the load as it exists at a particular height of the load, such as the width of the load when measured at approximately 30 inches above the floor level of the pallet bottom 18. The system 2 includes at least one controller 20 for electrical connection to the stretch wrap machine 22, wherein the controller 20 is configured to receive the measurement values and compare those values to stored information relating to pallet 8 dimensions and/or tolerances. For example, the stored information may include ranges of values for pallet sizes, such as typical ranges for pallet loads on a 36 inch wide pallet or a 40 inch wide pallet or a 52 inch wide pallet. The system 2 further includes a signal generator (not shown) associated with and coupled to the controller 20, the signal generator being configured to provide a differential signal to the stretch wrap machine 22 based on comparison of the measurement values to the stored information.

Thus, the present invention provides a sensing and control system for a floor-mounted stretch wrap assembly 4, whereby sensor beams 12 are utilized to obtain the measurements of a pallet load 8, such that a differential signal is transmitted to the stretch wrap device 22. The differential signal may be used to activate or prohibit the wrapping sequence, such as a signal identifying a load out of proper position at a stretch wrap station 24, as the sensors 10 are utilized to detect alignment or misalignment of the pallet load 8. Alternatively, the differential signal may differ according to identification of differing dimensions of a pallet load or class of pallet load size, information which may be used to adjust the speed of the film being applied by the stretch wrap device 22 such as by adjustment of the speed of the motor (not shown) at a prestretch carriage device 26 that rotates in a carriage area 27 about a load 8 being wrapped. In this embodiment, the sensors 10 are used to identify the width of the pallet load, that information is transmitted to a processor for comparison to pre-programmed information regarding pallet size and used to determine and control the appropriate speed of the motor of the prestretch carriage 26. Thus, the differential signal transmitted to the wrap assembly 22 of this embodiment is a signal that initiates control of the motor speed and thereby adjusts the speed of the stretch wrap film.

The present invention serves as a detection and control system for a floor-loaded, non-automated apparatus 4, in which pallets 8 are loaded by forklifts or pallet jacks into position at stations 24 for wrapping, rather than being placed on a conveyor belt of an automated system. Correct manual positioning of a pallet is challenging, and this challenge is amplified in multi-station system such as that disclosed in co-pending U.S. patent application Ser. No. 12/178,473, filed Jul. 23, 2008, the disclosure of which is incorporated herein by reference. As shown in FIG. 1 of the present application, which depicts a stretch wrap apparatus 4 that includes three stations 24 for wrapping pallet loads 8 in position at a respective stretch wrap station 24, each of the pallet loads 8 are manually placed in position, at an appropriate distance apart from one another.

This system may be used with a variety of floor-loaded wrapping machines, including the single-post structure 28 shown in FIG. 1 and the four-post structure 30 shown in FIG. 2 (which shows a stretch wrapping station from above). A four-post system comprises arms mounted to four posts rather than a single post, providing increased stability to allow, for example, faster spinning of wrapping heads. As seen in FIG. 2, when the system is coupled to a four-post structure, the sensors 10 may be mounted directly onto a post 30 of the apparatus (as opposed to a separate stand where the post is absent, such as the single-post structure of FIG. 1). In either case, the sensors 10 are preferably mounted at approximately 30 inches above the floor, a height determined to be at least half the load height. In the embodiment where a single sensor 10 a is used, the sensor 10 a scans two faces 14, 16 of the positioned pallet 8 to obtain measurements of the width and depth dimensions of the pallet 8. At least one other sensor 10 b is mounted at another location about the load wrapping station 24, as shown in FIG. 2, preferably positioned at an opposite corner of the station 24, or as shown in FIG. 3, positioned at an adjacent corner of the wrapping station 24.

In a preferred embodiment, such as shown in FIG. 1, the sensors 10 are comprised of laser sensors, each positioned to emit a beam on at least a side of the load 8. As shown in FIG. 1, the stretch wrap apparatus 4 includes three stations 24 for wrapping pallet loads 8, each station 24 shown with a pallet load 8 that is at or near the proper position for the stretch wrap to be applied by a device 26 of the stretch wrap machine 22. At each station 24 of the apparatus 4, at least one laser sensor 10, and preferably at least two laser sensors 10 a, 10 b, obtains measurements of the pallet load 8 which is then used to initiate a signal for the apparatus, such as a signal identifying whether the pallet is correctly positioned with respect to the wrap machine 22. In an alternate embodiment, the laser sensor 10 may be used to identify outer dimensions of the pallet for adjustment of the stretch wrap film speed and/or adjustment of the rotational area 27 of the carriage 26 of the wrapping apparatus relative the load 8, which is adjusted by the control of the assembly transmitting an appropriate signal identifying a dimension of the load or by comparing the load dimensions to stored data (residing in a data memory device of the controller 20) relating to categories of pallet load sizes. An example of a laser sensor 10 for use with the present invention is the TiM3xx Laser Scanner manufactured by SICK AG. As used with a stretch wrap machine 22 such as that of FIG. 1, at least one laser sensor 10 is mounted adjacent the a wrapping station 24 of the apparatus, preferably on a non-moveable stand or post 32 and facing a corner of a pallet position. The laser device 10 is positioned at a location generally along a diagonal line 34 through a pallet load 8 when placed in the station 24, such as shown in FIGS. 2 and 3. As such, the laser 10 is in position to scan at least an extent of two sides 14, 16 of the load 8, as shown in the Figures. Thus, a single laser 10 is capable of obtaining measurements that may be used to determine the size of the load, i.e., at least measuring the load width along two sides to determine the size of the rectangular or square load.

In one embodiment, each laser sensor 10 assigns a value to the measurement of the load 8. That value is transmitted to a controller 20 and used to determine the position of the load 8 and identify whether the load 8 is skewed in the station 24 or is in an acceptable orientation for commencing the wrapping sequence. Such calculations or determinations are preferably made at a processor of the controller 20 that receives electrical signal from each sensor 10, such as signals transmitted from each laser 10 to the processor 24 via conduit 36 of the apparatus 4. In the embodiment shown in FIG. 1, each sensor 10 is electrically connected to a main controller 20 via a sub-controller or junction station 38. In this manner, it is contemplated that signals from each sensor 10 may pass directly to the master controller 20, or signals from each sensor device 10 may be transmitted to a respective sub-controller 38 for manipulation or processing of the signal information prior to data being transmitted to the master controller 20. At least one computer processor (not shown) is provided at the master controller 20 and/or the sub-controller 38 for processing the information received relative the sensor signal and comparing that information with pre-loaded information in memory associated with the processor, including data regarding the acceptable range of the pallet load position and/or the range of pallet load size.

Multiple sensors 10 are used to obtain additional and comparative measurements of the pallet load 8. As shown in FIGS. 1-3 at least two sensors 10 a, 10 b are preferably positioned about each stretch wrap station 24 of the apparatus 4. In the embodiment shown in FIGS. 1 and 2, sensors 10 a, 10 b are positioned at opposed sides of each station 24, generally at opposite corners of the pallet load position, each generally positioned along a diagonal line 34. In this embodiment, each sensor 10 a, 10 b is configured and positioned to cast a layer beam 12 to identify the width of two sides 14, 16 of the load 8, thus measuring each side of the load residing at one or more specified load height. In the embodiment shown and described, each sensor 10 a, 10 b is a laser capable of obtaining such measurements of at least an extent of the load width. Data from the measured values is then compared to pre-programmed values to determine the width dimensions of the pallet load, such as determining whether the pallet load is one of three alternate classes of pallet sizes, such as pallet loads of 40 inches by 48 inches, 36 inches by 36 inches, or 52 inches by 52 inches. The processor 20 may then assign an appropriate stretch film speed according to the respective general sizes of pallet loads using pre-programmed information of the processor data memory.

In operation, after an operator loads the one or more pallet loads 8 in the stations 24 of the apparatus 4, the laser sensors 10 of each station 24 detecting a pallet load is configured to measure at least two faces 14, 16 of the pallet load 8. Information from such measurements is then processed at the controller 20 computer processor. The controller 20 subsequently provides feedback regarding the machine's tolerances for the rotation of the carriage 26 of the machine around the pallet for wrapping the pallet load. If the measurements obtained are within of the allowed tolerances of position and/or dimensions of the load, an immediate signal to the forklift operator, via visual or audio indicators, may be provided. For example, different colored lights (green, yellow, red), flashing lights of steady or varying frequency (not shown), or audio tones, may be used to signal pallet position information to the operator. If the pallet 8 is incorrectly placed at a station 24, the operator can then make necessary adjustments to the position of the one or more pallets to ensure proper positioning, before the machine 22 begins the wrapping sequence at any station 24. Further, regardless of whether such signal information is provided to the operator, the controller is preferably configured to utilize the measurement values to send a signal to each respective stretch wrap machine 22 of the apparatus 4, indicating that the stretch wrap operation should be initiated.

Further, the controller 20 is preferably configured to utilize the load measurement values to send adjustable signal to the prestretch carriage 26 of each respective stretch wrap device 22 of the apparatus 4, to adjust the speed of the motor of the carriage 26 and thereby control the speed of the film in the wrapping sequence. In this aspect of the invention, the prestretch carriage 26 of each stretch wrap machine 22 rotates about the pallet load on a fixed path. In common devices, the speed of the carriage 26 may be increased or decreased at certain locations about the load 8 to accommodate for the distance between the load 8 and the apparatus 26 applying the film. The apparatus 4 of the present invention optionally utilizes the load size determination (the width measurements) to vary the speed of the film applied rather than requiring adjusted speed of the arm of the prestretch carriage device 26. Specifically, the controller 20 is configured to utilize the load measurement values to send adjustable signal to the motor of the prestretch carriage 26, thereby adjusting the speed of the film being applied to the load 8.

Therefore, in addition to determining pallet placement tolerances and communicating a signal regarding such information for operation of the assembly, the pallet measurements obtained by the sensors can be used by the controller 20 to essentially determine the distance between the prestretch carriage device 26 and the pallet load 8, and to communicate such information to the prestretch device 26 to adjust the amount of film needed and applied to wrap a pallet 8. The prestretch carriage 26 includes a motor that supplies the film and stretches the film as it is applied to the pallet load. Different sized pallets demand that different amount of films be delivered to the pallet to ensure a tight wrap, because too much film on a small pallet will result in loose film. When pallets are manually loaded, the distance between the film carriage and pallet may change from pallet to pallet even when the pallet is the same size. However, the system of the present invention compensates for the respective size of the load 8, which defines the distance between the pallet load and the prestretch carriage, such that the prestretch carriage is adapted to deliver film at the appropriate speed to ensure a tight wrap of the pallet load. The ability to predetermine how much film is needed and when film is needed allows for a smother unwind of film (less forceful acceleration and deceleration of film), which offers a number of benefits.

As shown in FIGS. 1-3, the laser sensors 10 measure the width of the sides 14, 16 of the pallet load 8, provides such data to the stretch wrap machine controller 20, which then processes the information with an algorithm to determine distance from the pallet to prestretch carriage on all sides. In combination with the laser sensor 10, an encoder (not shown) is coupled to the arm that holds the prestretch carriage 26. The encoder transmits data to the controller 20, specifying the exact position of the carriage 26. With the carriage position data from the encoder and the pallet position data from the sensors 10, the distance between the arm and the pallet at all points around the pallet is determined. The system 2 thus allows predetermination of the amount of film needed to wrap a pallet load 8 prior to commencing the wrapping sequence. Thus, when the film is needed, it is delivered in a more consistent manner. This provides the advantages of (i) controlling film tension to the pallet more accurately; (ii) determining an exact amount film needed to wrap a load to ensure that more film than needed is not used; and (iii) the ability to use thinner films rather than thicker, more expensive films.

An alternative embodiment for determining pallet placement tolerances and communicating a signal regarding the pallet placement at a station 24 is also contemplated. In this embodiment, two or more photo eyes 40, 42, 44 are used to determine the positioning of a floor-loaded pallet 8. As shown in FIGS. 4 and 5, an embodiment comprising at least two photo eyes, the first photo eye 40 is positioned above the floor-loaded pallet 8 for identifying the presence of the load, and a second photo eye 42 is positioned adjacent the pallet load to identify whether the load is in a suitable position for the wrapping sequence to commence. This is preferably achieved by the first photo eye 40 being directed within the area for the pallet within the station 24, and the second photo eye 42 having a generally horizontal detection beam passing adjacent and outside the acceptable location for the pallet load 8. The second photo eye 42 is positioned such that a beam will detect obstruction by the pallet, thereby identifying the pallet to be outside the proper area of the station 24. A processor 20 receives input from the first photo eye 40 and is capable of receiving input from the second photo eye 42, and processes the information to determine whether the detected pallet 8 is in suitable position. A signal is then generated by the processor 20 to commence the wrapping operation when the proper conditions are met. Further, an audio and/or visual signal may be activated by the processor 20 to provide the pallet forklift operator information of the status of the pallet, i.e., whether the pallet is within the acceptable tolerances to initiate the wrapping sequence.

In the embodiment shown in FIG. 4, a third photo eye 44 is provided at the opposite end of the pallet station 24 relative the second photo eye 42. The third photo eye 44 is positioned such that a detection beam 45 will identify whether the opposite side of the pallet load 8 is in position by determining whether the load obstructs the beam 45. Further, in an embodiment it is contemplated that the position of horizontal photo eye beams 45 of the second and/or third photo eye 42, 44 may be adjusted to accommodate for differing sizes of pallets, or may include multiple beams 45 at each photo eye device 42, 44 as is shown in FIG. 4. The embodiment utilizing one or more photo eyes does not necessarily detect pallet skew or misalignment, and thereby guiderails or bumper rails 46 may be deployed to assure that the pallet 8 is acceptably aligned in the station 24. This embodiment of the system could be used with a single-headed machine or with machines having varying numbers of wrapping heads.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any equivalent thereof. 

What is claimed is:
 1. A pallet load sensing and control system of a floor-loaded stretch wrap apparatus having an arm that rotates around a pallet to wrap the pallet in stretch wrap, the system comprising: a laser sensor device for measuring at least an extent of a first face and at least an extent of a second face of a floor-loaded pallet and generating assigned values for said measurements; a controller for electrical connection to the stretch wrap machine, said controller configured for receiving said measurement values and comparing said values to stored information regarding pallet tolerances; and a signal generator coupled to the controller, the signal generator being configured to provide a differential signal based on comparison of the measurement values to the stored information.
 2. The system of claim 1 wherein said measurement values are compared to stored information of the acceptable tolerances for the pallet being in correct position for initiating a wrap sequence of the stretch wrap apparatus.
 3. The system of claim 1 wherein said measurement values are compared to stored information of pallet size and wherein the signal generator provides a differential signal for adjusting the speed of the shrink wrap apparatus.
 4. The system of claim 3 wherein the controller is configured to identify the pallet dimensions within a tolerance of a pallet size, and wherein said signal generator is configured to provide alternate signals to the wrap assembly depending on the pallet size.
 5. The system of claim 4 wherein said signal generator is electrically connected to a frequency drive of a motor of the wrap assembly, such that the motor is run slower for a smaller pallet size and the motor is run faster for a larger pallet size.
 6. The system of claim 5 wherein the signal generator initiates a different signal depending upon the measurement values residing within one of alternate pallet sizes.
 7. The system of claim 3 wherein a drive motor of the wrap assembly is driven by a current that has a lower frequency when a smaller pallet is detected and said motor is driven by a current of higher frequency when a larger pallet is detected.
 8. The system of claim 7 wherein a drive motor of the wrap assembly is driven by a 60 Hz frequency current when a particular pallet size is identified and said motor is driven by a current less than 60 Hz when a smaller pallet size is identified.
 9. The system of claim 7 wherein a drive motor of the wrap assembly is driven by a 60 Hz frequency current when a measurement value is about 52 inches and said motor is driven by lower frequency current when the greatest measurement value is about 40 inches.
 10. The system of claim 1 wherein said controller further comprises: a first processor for calculating pallet position data comprising the distance from the pallet on all sides to a prestretch carriage to an arm of the wrapping assembly; an encoder coupled to the arm, wherein said encoder transmits position data comprising the position of the arm relative a reference position; and a second processor for calculating the distance between the arm and the pallet at points around the pallet using the arm position data and the pallet position data.
 11. A pallet load sensing and control system for use with a floor-loaded stretch wrap apparatus having an arm with a prestretch carriage configured to rotate around a pallet to wrap the pallet in stretch wrap, the system comprising: a sensor for determining at least a dimension of first face and a dimension of a second face of a floor-loaded pallet and generating values of the measurements; a controller coupled to the stretch wrap machine, the controller receiving the dimension values and calculating pallet position data relative a reference position; wherein said controller provides a signal to the stretch wrap apparatus to activate a shrink wrap sequence if the pallet is within a predetermined location in relation to the reference position.
 12. The system of claim 11 wherein said controller further comprises: a first processor for calculating pallet position data within a zone of a wrapping apparatus and an encoder coupled to the arm, wherein said encoder transmits position data comprising the position of the arm relative a reference position; and said controller further comprising a second processor for calculating the distance between the arm and the pallet at points around the pallet using the arm position data and the pallet position data.
 13. A pallet load sensing and control system for use with a floor-loaded stretch wrap apparatus having an arm with a prestretch carriage configured to rotate around a pallet to wrap the pallet in stretch wrap, the system comprising: at least a first sensor for identifying a position of at least a side of a pallet load and a second sensor for identifying a position of another portion of the load; a controller coupled to the stretch wrap machine, the controller electrically connected to receive signals from the first and second sensors and having a computer processor for calculating the position of at least a portion of the load and said controller thereby generating a signal transmitted to the stretch wrap apparatus to identify when a pallet is in position and misalignment is not detected.
 14. An apparatus for controlling an amount of pre-stretched packing film applied about a load, comprising: at least one primary sensor positioned about a packing station for a palletized load, said sensor configured to emit a detection beam directed toward a load wrapping station and configured to identify a border of the load when positioned in said station and generate a primary sensor signal; at least one secondary sensor positioned relative said packing station, said secondary sensor configured to emit a secondary detection beam at a predetermined position relative the wrapping station, such that said secondary sensor is able to detect the presence of the load at said predetermined position; and thereby generates a secondary sensor signal; a processor electronically connected to said primary and secondary sensors to receive the primary signal of the load and to receive the secondary signal, said processor configured to initiate a warning condition in the event the load is misaligned within the wrapping station.
 15. The apparatus of claim 14, wherein the secondary sensor is positioned to emit said sensor beam outside a border of said wrapping station.
 16. The apparatus of claim 15 wherein said secondary sensor generates an electric signal identifying mis-alignment of the load, and said signal being transmitted to the processor wherein the processor is programmed to prevent the wrapping apparatus from initiating a wrapping sequence.
 17. The apparatus of claim 14 wherein the primary sensor is a laser and said secondary sensor is an electric eye.
 18. The apparatus of claim 17 wherein said primary sensor laser measures a distance to the load and the processor operates to compare said distance measurement with information regarding a border of said wrapping station.
 19. A pallet load sensing system for use with a floor-loaded stretch wrap machine having an arm that rotates around a pallet to wrap the pallet load with stretch wrap, the system comprising: a first photo eye, said first photo eye positioned opposite one face of a floor-loaded pallet load for generating a signal identifying the presence of a pallet load; a second photo eye, said second photo eye positioned adjacent a load station area and directing a photo eye beam to detect obstruction of a photo eye beam by load; a processor for receiving said signal of the first photo eye and a signal from the second photo eye, said processor having a computer processor configured for determining whether a load is in proper position for operation of the stretch wrap apparatus; a signal generator in communication with the processor for providing a signal to initiate operation of the stretch wrapping assembly to commence the wrapping sequence of the load.
 20. The system of claim 19 further comprising two photo eyes deployed about the load station, each positioned at opposed ends of the station to detect obstruction of respective photo eye beams by the load. 